THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[18:00:12]

WOLF BLITZER, CNN HOST: Happening now, breaking news: Captured.

One of the world's most wanted terrorist suspects now in custody. Is he the mysterious man in the hat? His escape from the Brussels Airport bombing was caught on video.

Urgent raids. Police are conducting new searches tonight amid fears that ISIS may now accelerate plans for another bombing. I will ask a top member of the Senate Intelligence Committee what he's learning.

Where is Trump? The Republican front-runner is out of sight, uncharacteristically quiet today, but tonight his team is working feverishly behind the scenes as Trump loses a new round in the battle for delegates.

And turf war. The Democrats try to one-up each other with their New York connections while distancing themselves from a public brawl that might hurt their party. Will there be bad blood when they debate in Brooklyn next week?

We want to welcome our viewers in the United States and around the world. I'm Wolf Blitzer. You're in THE SITUATION ROOM.

ANNOUNCER: This is CNN breaking news.

BLITZER: Let's get right to the breaking news this hour. More searches are under way tonight, after the arrest of a fugitive terrorist suspect, a couple of them, in fact, with ties to the Paris and Brussels attacks.

Among those captured, Mohamed Abrini, alleged to be a pivotal figure in the terror cell that's caused mass carnage in Europe and is believed to be plotting new attacks. Also tonight, prosecutors are trying to determine if Abrini is the so-called man in the hat, the third Brussels Airport attacker who survived the bombing and fled the scene.

We're also following major new developments in the presidential race here in the United States, including new details on Donald Trump's strategy to win delegates and overcome a series of new setbacks.

Senator Mark Warner of Virginia, he's a key member of the Senate Intelligence Committee. He is standing by live, along with our correspondents, analysts and newsmakers.

Up first, let's go to our chief national security correspondent, Jim Sciutto, with more on the terror arrests.

Jim, tell us what you're learning.

JIM SCIUTTO, CNN CHIEF NATIONAL SECURITY CORRESPONDENT: Wolf, we know that both of these men are central, not peripheral to the two deadliest terror attacks in Europe of the last decade in Paris and more recently in Brussels.

Abrini even driving one of the lead Paris terrorists to and from the deadly rampage there. The key question now, is he the same man seen with the Brussels attackers before they struck again?

(BEGIN VIDEOTAPE)

SCIUTTO (voice-over): This is the moment Belgian police arrest one of the most wanted terrorists in Europe, Mohamed Abrini, with ties to several of the Paris attackers, captured in Brussels today.

Abrini has multiple connections to the deadliest terror attack in Europe in more than a decade.

PETER BERGEN, CNN NATIONAL SECURITY ANALYST: It's quite significant because he is one of the last people that they found who played a critical role in the Paris attacks. He also appears to have played a critical role in the Brussels attacks. He links these two cells together.

SCIUTTO: Abrini was caught on surveillance video driving Salah Abdeslam, one of the lead Paris terrorists, to the French capital two days before the attacks. The car seen at this gas station is the same vehicle used to transport some of the terrorists that deadly night.

Abrini also rented an apartment where two of the Paris attackers stayed. And after the Paris rampage, he returned to Belgium with Abdeslam before both disappeared.

BERGEN: He doesn't talk. What is in his computer, what is in his cell phones, what are in the papers that are found at the place where he was arrested and the pocket litter he's carrying, you have to analyze that very quickly.

Questions now as to whether Abrini is the so-called man in the hat seen with the two suicide bombers at the Brussels Airport before he escaped on foot.

Just yesterday, police released a series of surveillance videos tracking his movements.

ERIC VAN DER SYPT, SPOKESMAN, BELGIAN FEDERAL PROSECUTOR: Investigators are verifying whether Abrini, Mohamed, can be positively identified as being the third person -- third person present during the attacks in Brussels National Airport, the so-called man with the hat.

SCIUTTO: Also arrested today, Osama Krayem. Belgium investigators are now trying to determine if he is the man seen at a Brussels metro station with a suicide bomber, Khalid El Bakraoui, before he detonated his explosives, killing 14 people and wounding 90.

Investigators believe that Krayem also bought the bags that held the explosive devices used in the airport attack. Police reportedly found the DNA of both Abrini and Krayem at the apartment in Schaerbeek where the Brussels attackers built their bombs.

BRIG. GEN. MARK KIMMITT (RET.), FORMER U.S. CENTRAL COMMAND DEPUTY DIRECTOR FOR PLANS AND STRATEGY: What they have got to do is widen the investigation, widen the intelligence gathering, make sure that the intelligence goes well beyond Belgium and France.

(END VIDEOTAPE)

SCIUTTO: The immediate focus now for European police is uncovering the rest of this vast terror network and, crucially, preventing new attacks.

[18:05:00]

You will remember that the Brussels attacks followed the arrest of Salah Abdeslam just three days later. The concern now is that the terrorists might act fearing that they will soon be discovered -- Wolf.

BLITZER: All right, that is a serious fear, indeed.

All right, Jim Sciutto, thanks very much.

Let's bring in our justice correspondent, Pamela Brown. She's also working her sources.

What are they saying, Pamela? How significant are today's arrests?

PAMELA BROWN, CNN JUSTICE CORRESPONDENT: Well, they're certainly significant, particularly with Abrini, because he was someone who authorities have been searching for forever since the Paris attacks.

So, these are some key players that have been taken off the chessboard. But officials I have been speaking to say that there are still a lot of other people in Europe connected to this network. And the concern is that these people, these ISIS terrorists, are plotting multiple attacks as we speak.

And so, in fact, the threat level is just the same as it was before these arrests, according to one official I spoke to. The big concern is that in the wake of this arrest, these arrests today, that anyone planning attacks would accelerate those plans out of concern that intelligence officials will track them down. We saw that after the arrest of Salah Abdeslam, Wolf.

BLITZER: A few days later, and that's what happened, a terror attack in Brussels.

We're showing our viewers, by the way, these live pictures. There are raids under way in Brussels right now. That's what we're showing, these live images coming in. It's after midnight in Brussels right now. We will see what develops. We're expecting some major news.

What about Mohamed Abrini? There's some suspicion he is actually that guy in the hat with the white jacket who has had that luggage cart at the airport.

BROWN: From the very beginning, Wolf, intelligence officials suspected he could be because of his ties to Abdeslam, because the man in the video is incognito. And Abrini would have an incentive to be in disguise, since his pictures have been plastered everywhere.

But in addition to that, Wolf, I'm told there's been additional intelligence gathered, indications that he could be the man in white, just establishing the network of these people, backtracking, process of elimination, ruling people out.

And so, through that process, they have been able to hone in more on him. But I'm told there were two other people officials also thought were the man in white. Turned out they weren't. And so officials are still cautious until they have that definitive proof in fact it is.

BLITZER: All right, Pamela, thanks very much. If you get more information, you will let us know right away.

Joining us now, a leading member of the Senate Intelligence Committee, Senator Mark Warner, Democrat of Virginia.

Senator, thanks very much for joining us.

What about this guy Mohamed Abrini? As you know, he was the subject of a massive manhunt since the Paris attacks back in November. Why do you think it took so long to capture him?

SEN. MARK WARNER (D), VIRGINIA: Well, Wolf, first of all, let's recognize the fact that it does look like the Belgian authorities have taken down two more members of this terrorist ring.

That's a step in the right direction. But I think it also lays out the fact that there's still not a level of information-sharing, both internally within each of these European countries and between countries. Unfortunately, it took us in our country 9/11 before we had the law enforcement and intel agencies cooperate in a better way.

It took the 7/7 event in the U.K. before they kind of got religion. It's taken now these two awful events, "Charlie Hebdo" and then the shootings. We were actually in France, a group of intel members, on the day of the Brussels attacks. And the French clearly had much better coordination now. They were -- there was some real concerns about the Belgian

authorities. And, frankly, all across Europe, there are silos between law enforcement, between external services, their internal services, and my fear is, will it take these kind of incidents in each country before they in effect get religion about how serious this is to take down and share this information?

BLITZER: Yes, they have got a lot of work to do over there.

As you know, Mohamed Abrini, he was one of Europe's most wanted individuals. What will his arrest mean potentially for helping to stop other terror attacks that may be in the works?

WARNER: Well, I think, as your reporters indicated, this is a right step in terms of he was one of -- it appears to be one of the major plotters.

But will this also signal to other plotters that they should go ahead and act? We have got to deal with this immediate cell, but, at the same time, continue to put pressure on Turkey, where a lot of these individuals come in and out of the war zone and can travel freely once they get through Turkey into the E.U.

We have got to continue in America to beef up our protections around our visa waiver program. And we have just got to make sure that the European law enforcement and intel services do a better job of sharing. It would be as if, in America, New York wouldn't share with New Jersey and wouldn't share with Virginia and they each had a separate FBI and CIA. That, in effect, is what's been the makeup of the services in Europe.

BLITZER: And even within countries, it's like that in Belgium. Some districts in Belgium don't share information with other districts in Belgium. They speak different languages. They speak French. They Flemish. They have got a problem there.

Are there other plotters at large, plotters who were involved in the Belgium attacks still at large?

[18:10:00]

WARNER: Yes, I have not been briefed on that specific cell. And, frankly, I wouldn't share that information if I had it.

I do believe from the press reports and others that it is -- that the Europeans are still very much on edge. I think there's a recognition, as we saw after the Paris attack, that then the subsequent Belgian attack, I think at least in Europe they ought to go ahead and raise the alert a little further.

And, again, the leadership, the political leaderships in each of these countries need to relay to their security services to make sure that they share this information. As has been pointed out now, some of the attackers in Belgium were actually made aware, the Belgian authorities were made aware of these individuals, but didn't follow up in a timely manner. BLITZER: As you know, the -- another one of these Paris attackers,

Salah Abdeslam, he was arrested just four days before the Brussels airport and metro attacks.

How concerned are you that Abrini's arrest could trigger another terrorist, because you're suggesting raise the alert right now?

WARNER: I'm saying within the European countries, I think there's -- I think we are at appropriate level of vigilance for what we know in terms of threat level.

I do think the Europeans, this is as much -- not so much necessarily just a threat level, as making sure the European political leadership conveys to their security services that they need to do a better job of sharing this information. They have got to break down the silos.

And, again, this is something, quite honestly, prior to 9/11, we had those same silos in America. They had the same silos in the U.K. before 7/7. And, unfortunately, it took a couple of attacks in France, I think, for the French to kind of have a greater level of internal and external cooperation.

BLITZER: The Belgian broadcaster VRT says that Abrini, Mohamed Abrini, was possibly the man in the hat sought in connection with the Brussels Airport attacks, the suspect seen in the surveillance video, seen walking next to two of the other suspected suicide bombers.

If that's the case, this would be a major breakthrough in learning a lot more about those Brussels attacks, wouldn't it?

WARNER: It would be a major breakthrough, but I think, as you -- we have seen, we don't know the full extent of this cell.

And, clearly, there are a number of other people that have gone into the war zone in Syria and Iraq, have come back radicalized. And this is not just a threat in France or Belgium. But, quite honestly, with the challenges in Germany, continuing challenges in the balance of Europe, my -- again, my greatest fear is that we don't have to go through horrible incidents in each of these individual countries before those individual countries decide that further vigilance, further resources in terms of tracking these terrorists, and then further cooperation both internally and externally, God forbid that we don't have to have these kind of events before other countries step up.

BLITZER: Senator Mark Warner of Virginia, thanks very much for joining us.

WARNER: Thank you, Wolf.

BLITZER: For more on what you can do to help the victims of the Brussels terrorist attacks, go to CNN.com/Impact, and you will Impact Your world.

Just ahead, we have more on the terror arrests coming in. Plus, we're going to tell you what's going on behind closed doors of

the Trump campaign right now, as the GOP front-runner stays put in New York before the primary. What's going on? We will tell you.

And the shifting tone in the Democratic presidential race. Can Bernie Sanders and Hillary Clinton put an ugly new brawl behind them?

(COMMERCIAL BREAK)

[18:18:05]

BLITZER: We're following breaking news, a new hunt for terrorists in Europe after police captured suspects linked to the Paris and Brussels terror attacks.

And there are fears tonight that the arrests could trigger the new attacks. Stand by for more on that. We're getting more information.

Right now, I want to turn to the presidential race here in the United States.

We're learning more about the Trump campaign's intensifying fight to win all those important delegates on a day when the front-runner suffered some new losses to Ted Cruz.

So, all of a sudden, today, we heard from the new convention adviser for the Trump campaign, Jim.

JIM ACOSTA, CNN SENIOR WHITE HOUSE CORRESPONDENT: That's right, Wolf. It is a new day for the Trump campaign in that regard.

Donald Trump is still laying low back in New York, but not Ted Cruz. He's out West to meet with potential donors here in Las Vegas before he appears at a Republican state convention in Colorado tomorrow, the only candidate to do so.

It's all part of this intense new phase of the campaign, the delegate fight.

(BEGIN VIDEOTAPE)

ACOSTA (voice-over): Inside Trump world, it's a new day in the GOP delegate battle. And Donald Trump's new general in charge of racking up the magic number needed to clinch the Republican nomination is predicting victory.

PAUL MANAFORT, TRUMP CONVENTION MANAGER: It will be apparent to the world that Trump is over the 1,237 number. And at that point in time, when it is apparent, everything is going to come together.

MANAFORT: This is an example of Donald Trump managing and the kind of leadership he will bring to the presidency after November. Campaigns have different phases.

ACOSTA: And while Manafort pushed back on the notion Lewandowski is being sidelined after a string of campaign setbacks, he made it clear he answers only to Trump.

[18:20:00]

MANAFORT: I listen to everybody, but I have one man whose voice sounds -- is louder than everybody else's.

ACOSTA: Manafort's rise comes as a crucial time, as Ted Cruz is implementing his own delegate strategy to grab them wherever he can. Case in point, this weekend, Cruz is scheduled to visit Colorado, where Republicans are holding their own convention to select delegates. Cruz picked up more delegates there today.

REP. KEN BUCK (R), COLORADO: The Cruz campaign has been successful in Colorado because we started earlier. We identified more of the grassroots supporters. I don't think that the other campaigns took this process seriously early enough.

ACOSTA: It's a trip Trump decided against, in the hopes of a landslide over Cruz in the New York primary. Trump was apparently working out of the office today, saying in a tweet: "So great to be in New York catching up on many things. Remember, I'm still running a major business while I campaign, and loving it."

SEN. TED CRUZ (R-TX), PRESIDENTIAL CANDIDATE: Look, we have a clear path forward to get to 1,237 delegates. It's difficult. We have got to win, and we have got to win consistently.

ACOSTA: Cruz told CNN's Dana Bash he's laughing off the R-rated welcome he's receiving in the Big Apple after he slammed Trump's New York values.

CRUZ: I laughed out loud. Look, I have never been popular with left- wing journalists or tabloids.

ACOSTA: Lagging behind in the delegate fight, John Kasich is making the case he won't be dead on arrival at the GOP Convention this summer.

ACOSTA: With a tough new ad, Kasich argues he still has the best shot of defeating Hillary Clinton, and he is warning voters Trump's make America great again message is a general election disaster.

GOV. JOHN KASICH (R-OH), PRESIDENTIAL CANDIDATE: We're not winning? We're winning on about everything. We are still the strongest country by far in the entire world and people ought to stop whining about America.

(END VIDEOTAPE)

ACOSTA: Now, as for Ted Cruz, he's courting some big donors here in Las Vegas. He will address a Republican Jewish group run by casino tycoon Sheldon Adelson tomorrow.

And after some downtime, Trump gets back on the campaign trail on Sunday. He will be appearing in Rochester, New York, Wolf. And the Trump campaign tells me that it's not just about New York when he's in that state. They say that that kind of campaigning in New York state gets exposure across the Northeast.

And, as we know, all of those states are coming up very soon, Wolf.

BLITZER: The week after New York, there's Pennsylvania, there's New Jersey, there's Connecticut, there's a whole bunch of other states as well. All right, thanks very much for that, Jim Acosta reporting.

Joining us now is a prominent Trump supporter in New York State, Congressman Chris Collins. He's joining us from Clarence, New York. That's just outside of Buffalo, New York.

How likely, Congressman, is it that this primary season will end in a contested convention in Cleveland?

REP. CHRIS COLLINS (R), NEW YORK: Well, you know, Wolf, none of us know for sure where we're headed.

But I do know Mr. Trump on April 19 is going to win, if not all of the delegates in New York, pretty much all of them. His support here is just through the roof. So, you pick up 95 delegates here. He's going to do extraordinarily well in Pennsylvania, New Jersey.

He does have a road to 1,237. It's going to be a tough road. But, you know, I think right now, he's got the team put together. He's made a few changes. And I think he's pivoting, if you will, to making sure he does get to 1,237. Only time will tell.

BLITZER: But, as you know, in order to get all 95 delegates in New York state on April 19, he's got to get more than 50 percent. Plus, he's got to win in every congressional district. What I hear you saying, you think that's doable?

COLLINS: Oh, there's no question it's doable. You know, some of the other statements the other candidates have made does not exactly endear them to New Yorkers.

We tend to be a group of pretty independent-minded individuals, and, you don't like it when someone takes a backhanded slap at you. But I would say he has a very, very good chance to win all 27 districts.

Mr. Trump, as you know, has hired a veteran political strategist, Paul Manafort, to run his delegate strategy. Is the Trump campaign now moving towards what we would call a more traditional campaign model?

COLLINS: Yes, I -- Wolf, I do think you're seeing a transition. You're going to see Mr. Trump more focused, I also believe, on a general election strategy in taking on who we believe the opponent will be in Hillary Clinton.

So, yes, these are the growing pains of a new candidate, and I think these are all very positive moves, putting an emphasis where it needs to be right now, which is the delegate fight, potential floor fight, as the rules have now been explained by the RNC. It's a very natural extension of the Trump campaign, as he continues to get more and more delegates, another 95 coming next Tuesday, we're hopeful, in New York, and just keep piling on.

BLITZER: He had a big rally out in Long Island, Bethpage, Long Island, Wednesday night.

But since then, yesterday and today, he's been quiet. He's tweeted, as you just saw, he's also busy running a major business. What is the strategy here? Why is he relatively silent on these critical days leading up to New York?

[18:25:10]

COLLINS: Well, the excitement here, frankly, is -- I know my phone is ringing off the hook. I'm getting e-mails from everyone. Can you help me get a better ticket to the rally on the 17th?

We believe we may well sell out HarborCenter. There's 18,000 people. That's where the hockey team the Buffalo Sabres play. Frankly, Mr. Trump doesn't need to do much of anything. The enthusiasm here is genuine. It's over the top. People are excited to have him coming to Rochester in a couple of days.

And for the big, big rally in Buffalo on the 17th, the excitement is like Stanley Cup final excitement, Wolf. And I think you know what I mean.

BLITZER: I certainly do. I know they love the Sabres and the Bills, for that matter, in Buffalo. I know that very, very well.

How is the Ted Cruz comment, going after so-called New York values -- I understand how it's playing in New York City. But how is it playing Upstate in Buffalo, Rochester, Syracuse, places like that?

COLLINS: Well, you mentioned it, not me, Wolf, and I just don't see the support there for the other candidates.

This is Trump country, whether it's the signs, and it's not just Republicans. It's Democrats. It's independents. We have a closed primary here, so not an open primary, like you have seen other places. If this was an open primary, you know, Trump's support would even be significantly more than it is, but even within the closed primary, only Republicans voting in the Republican primary.

He's got the support of and endorsement of most of the county chairs, the 62 counties in New York. Certainly, here in Erie County, he's got the endorsement of the full committee. We're the largest Upstate county in New York. And there's a saying. You don't win New York without winning Erie County. And Donald Trump, and that's why he's got his emphasis here.

It's also why you're seeing the emphasis put out by Bernie Sanders and Hillary Clinton. It all comes down to Buffalo and Erie County.

BLITZER: My hometown, a great place, indeed.

All right, thanks very much, Congressman, for coming in.

COLLINS: Happy to be with you, Wolf.

BLITZER: Thank you.

Donald Trump will join Anderson Cooper this Tuesday night for a CNN town hall, 9:00 p.m. Eastern. You will want to check it out.

You heard Paul Manafort say that, yes, Corey Lewandowski is the campaign manager, but he, Manafort, reports directly to Donald Trump. What do you make of this?

MARK PRESTON, CNN POLITICS EXECUTIVE EDITOR: Well, I think that's an important message that he is sending to Washington insiders, that he's in control of trying to get Donald Trump to 1,237 delegates that's needed to win the nomination. Paul Manafort well known within Republican circles. Very known here in Washington, D.C. Had he looked subservient to Corey Lewandowski, I don't think that would make him effective, as Donald Trump is trying to secure this nomination.

BLITZER: Rebecca, you wrote an article saying these other Republican senators, they're very reluctant to get in there and endorse Ted Cruz. He's got two, maybe three supporters so far that have publicly said they're going to support him. What's the problem here?

REBECCA BERG, NATIONAL POLITICAL REPORTER, REAL CLEAR POLITICS: Right. So reluctant is maybe a generous word to use in this case. Because really, they all just genuinely deeply dislike Ted Cruz. And even with Trump surging and on his way to potentially winning the Republican nomination or being in a strong position in open convention, these senators dislike Ted Cruz so much that they can't bring themselves, even in the face of Trump, to support him.

I mean, your interview with Senator Risch the other day really illustrated that perfectly, I think, because he admitted Ted Cruz is really the best candidate that remains for Republicans who don't want Trump to win the nomination, but at the same time, Risch couldn't call that an endorsement, even as he said he hopes Ted Cruz wins the nomination. It's really an amazing dynamic and I think sort of an unprecedented.

BLITZER: Yes. I know there are some Republican senators, you know, who -- they really don't like Donald Trump, but they don't like Ted Cruz even more than they don't like Donald Trump. That's a problem that they have right over there. We'll see if that changes.

Peter, Trump's campaign, as you know, canceled some trips to California, to Colorado. He's staying in New York. There's an issue, though. He hasn't been seen yesterday or today. Had a big rally Wednesday night. What do you think is going on over here as he's sort of been invisible for the last two days?

PETER BEINART, CNN POLITICAL COMMENTATOR: Yes. It's very strange for a candidate who's built his entire campaign on dominating the media landscape. And I think a lot of people thought that, after Wisconsin, he would do something big and high-profile and maybe, you know, controversial as he has in the past to basically get everyone talking about him. He hasn't done that. It's not entirely clear why.

I mean, again, in some ways, Donald Trump is unconventional politician. Very unconventional. Maybe he really did feel like he needed to do some work on his business.

[18:35:12] I also think there's clearly been a lot of internal churning in the Trump campaign. So maybe we're seeing the beginning of a somewhat different style. Maybe Paul Manafort is going to change the nature of the Trump campaign.

How much Donald Trump can really be controlled is another question. But it seems like they're trying to do something different.

BLITZER: Sara, you've been covering the Trump campaign now for months and months. You heard Paul Manafort tell Chris Cuomo this morning on CNN's "NEW DAY" they will have the 1,237, that magic number of delegates they need, by California -- what's that? -- June 7, or so. What's their plan to reach that magic number by California?

SARA MURRAY, CNN POLITICAL CORRESPONDENT: Well, as you might imagine, they're not exactly laying out their entire strategy, but I think the fact that they are going so big in New York. I mean, when you talk to members of his campaign here, they do want to win every single delegate or come as close as possible.

And looking ahead, they're looking to places like Pennsylvania, where a number of these delegates will be unbound. That's been a little bit of a struggle for Trump so far. But they feel like they can do well, and they're going to be making an aggressive push there.

They also feel like they're going to do really well generally in these mid-Atlantic states that are coming up April 26.

I think the question is, can you do well enough that you really just need to scrape up a little bit in California and you can make it to Cleveland with all of the delegates you need? I think that it is a very narrow path for them, and that is why you're seeing them buckle down and bring in someone like Paul Manafort.

We talk about him as the convention manager. We're not just talking about him being behind the scenes and working on these state conventions and planning for a second ballot. Because that's not what they're doing. They're planning for the primaries ahead to get as many delegates as possible so they can show up in Cleveland with Donald Trump as the nominee.

BLITZER: Yes. They don't want to reach a second or third ballot. They want to do it on the first ballot.

All right. Everyone stand by. We're getting some new information coming into THE SITUATION ROOM on why the former president of the United States, Bill Clinton, has now almost apologized.

(COMMERCIAL BREAK)

[18:41:25] BLITZER: We're back with our political team and the Democrats on damage control right now after their presidential contest started sounding a little like the Republicans'.

We're following the fallout from Bernie Sanders' brawl with Hillary Clinton over whether or not she's qualified to be president.

JEFF ZELENY, CNN SENIOR WASHINGTON CORRESPONDENT: No doubt about it, Wolf. Certainly a cooling of the rhetoric here. At least publicly by the two candidates themselves.

But behind the scenes inside the campaigns, Wolf, I can tell you still so contentious.

Bernie Sanders is planning to take this all the way to the convention, a contested convention even. The Clinton campaign knows there's one way to stop this. That's win big here in New York.

(BEGIN VIDEOTAPE)

ZELENY (voice-over): Tonight an apparent cease-fire in the heated Democratic presidential race. Bernie Sanders backing down after repeatedly saying Hillary Clinton is not qualified to be president.

SEN. BERNIE SANDERS (D-VT), PRESIDENTIAL CANDIDATE: Does she have the experience? Obviously, she does. She was secretary of state, a U.S. senator, I thought an outstanding first lady in many respects, breaking the mold.

ZELENY: The war of words cooling for a moment.

UNIDENTIFIED FEMALE: Do you believe he's qualified to be president?

HILLARY CLINTON (D), PRESIDENTIAL CANDIDATE: Yes. You know, as I said, I would take him over Donald Trump or Ted Cruz any day.

ZELENY: But the race remains highly contentious.

CLINTON: You may have heard Senator Sanders say I'm unqualified to be president. Well, seriously -- seriously, I've been called a lot of things over the years, but "unqualified" has not been one of them.

ZELENY: It's a bitter fight for the New York primary...

SANDERS: Thank you, South Bronx!

ZELENY: ... with both sides staking out their own turf. Visiting Buffalo today, Clinton took a page out of the playbook from her two U.S. Senate wins here.

CLINTON: I am so excited to be here and to see the extraordinary achievements of this community.

ZELENY: Sanders went home to Brooklyn to the streets of his childhood, reminding voters he's a New Yorker by blood.

SANDERS: I spent the first 18 years of my life in apartment 2-C right here.

ZELENY: The race for the White House has taken a decidedly local turn, with the nerve centers of both campaigns in Brooklyn, each other taking on the style of its candidate.

Inside the Sanders office, supporters are trying to channel his momentum into a New York upset.

ROBERT BECKER, SANDERS DEPUTY NATIONAL FIELD DIRECTOR: Every state we've gone to, we've been told exactly what we can't do, and we continue to defy the odds and win.

ZELENY: At Clinton headquarters, a far larger team is trying to protect Clinton's front-runner status.

UNIDENTIFIED FEMALE: I'm calling hoping that we have your support for Hillary Clinton.

ZELENY: Today on CNN, Sanders' campaign manager, Jeff Weaver, said his team is gearing up for a convention floor fight. JEFF WEAVER, SANDERS CAMPAIGN MANAGER: We have many people dealing

(ph) with the campaign who have floor experience in the Democratic Party. And so we're looking at all of our options.

ROBBY MOOK, CLINTON CAMPAIGN MANAGER: The stakes are so high here for Democrats, for Americans, that -- that Senator Sanders will believe in the importance of bringing this party together and making sure that the White House stays in Democratic hands.

ZELENY: On the campaign trail in Pennsylvania today, former president, Bill Clinton sought to move beyond his heated exchange with protesters on Thursday, whom he tangled with for 15 minutes.

BILL CLINTON, FORMER PRESIDENT OF THE UNITED STATES: It bothers me now when that happens. So I did something yesterday in Philadelphia. I almost want to apologize for it.

(END VIDEOTAPE)

ZELENY: Now, a short time ago tonight in Erie, Pennsylvania, Bill Clinton was asked if he believes that gender played a role in Senator Sanders' questioning the qualifications of Hillary Clinton.

[18:45:00] Listen to what he said.

(BEGIN VIDEO CLIP)

B. CLINTON: Yes, I think there's some different standards. Some of them are subconscious.

(END VIDEO CLIP)

ZELENY: So there you have that playing out. And one other side note, wolf, the campaign from New York is on here in full, but Bernie Sanders is taking a detour next week to go to the Vatican to speak tune economic conference there with Pope Francis, certainly not a bad way to reach out to Catholic voters here in New York as well -- Wolf.

BLITZER: You're absolutely right.

All right. Jeff, thank you very much.

Peter, let's talk about Bill Clinton's almost apology today. He said he went too far with that angry exchange he had with those protesters from Black Lives Matter. You just heard him say what he had to say. How is this going to play out?

PETER BEINART, CNN POLITICAL COMMENTATOR: I think the Clinton campaign would like to get this controversy over with them as quickly as possible. Remember, the main stay of Hillary Clinton's support in this presidential race has been African-Americans. It's their support among African-Americans that is a critical difference because Bernie Sanders in many states has won white voters. Now, not all African-Americans are going to -- black lives matter

about everything. But Hillary Clinton made it clear that she was going to make opposition to mass incarceration, a central element of her campaign. What Bill Clinton did was he defended the tough on crime policies of his administration back in the 1990s. I actually think it's an interesting intellectual debate to be had inside the Democratic Party, but it's not one that Hillary Clinton wants to be having right now.

BLITZER: And you heard, Rebecca, what Bill Clinton just said about whether the attacks against Hillary Clinton from Bernie Sanders, that she's not necessarily qualified to be president, that there may have been some subconscious issue there, different standard for her because she's a woman. What did you think of that?

REBECCA BERG, NATIONAL POLITICAL REPORTER, REAL CLEAR POLITICS: It was a very diplomatic way of phrasing it for Bill Clinton, saying it was subconscious. Bill Clinton and certainly Hillary Clinton don't want to be in a place where they are calling Bernie Sanders sexist. That doesn't do their campaign any favors. And it certainly won't help them winning over his supporters later when they are trying to unite this party if she wins the nomination.

But, certainly, you hear a lot of Hillary Clinton's supporters coming out and using the word sexist with Bernie Sanders calling her unqualified. And I think this is something we're going to hear about in the debate next week.

BLITZER: Bernie Sanders launched an attack on General Electric, claiming the company, in his words, "was destroying the moral fabric of the country." I want you to listen to what he told -- Bernie Sanders told in that interview with "The New York Daily News" editorial board.

(BEGIN AUDIO CLIP)

SEN. BERNIE SANDERS (I-VT), PRESIDENTIAL CANDIDATE: General Electric was created in this current by American workers and American consumers. What we have seen over the many years is shutting down of many major plants in this country. Sending jobs to low-wage countries.

MARK PRESTON, CNN POLITICS EXECUTIVE EDITOR: Well, Wolf, our CNN money analysis shows how GE's footprint has indeed dropped dramatically over the past two decades. Back in 1995, roughly 68 percent of GE's 220,000 total employees were in the U.S.

By 2005, the percentage declined to 51 percent. And by the end of 2015, just 38 percent of these employees were in the U.S. GE's total global workforce which has increased to 330,000 people. But it employs fewer American workers today, 125,000, versus 161,000 in 2005. GE's factories tell a similar story. A majority of its expansion has

happened overseas. GE has 10 fewer U.S. plants today than a decade ago, but the number of factors overseas has risen by 58. While it used to be split, about evenly. Today, 59 percent of GE's plants are on foreign soil.

The verdict, we rate in this statement, Wolf -- true.

BLITZER: Interesting. Very much -- thanks very much for that, Mark.

Sara, quickly to you, I just want to get your thought on this -- the turmoil, I don't know turmoil, the fighting that's going on, on the Democratic side right now. Do you think it is going to continue or will there be the cease-fire?

SARA MURRAY, CNN POLITICAL REPORTER: Well, Wolf, I think you will definitely see some of this contrast because as you can see Hillary Clinton wants to wrap this up. And Bernie Sanders is now threatening a contested convention. They're sounding more and more like the Republican side of the aisle, and I think we've seen how nasty it has become.

But I also think we have to look at the voters on the Democratic side, what they want, that has similarities to the Republican side as well. I mean, there is a base of the Democratic Party that is really unhappy with the kind of standard bearer that they're seeing, when they elect someone who says things will be different, and they feel like it haven't gotten the change they wanted and I think that's why you're seeing the surge for the support for Bernie Sanders. And it's clearly been much tougher for Hillary Clinton to move beyond that, than she expected.

BLITZER: And, Peter, Senator Sanders, we just heard announcing a trip to Vatican City for a conference on social justice, environmental sustainability on the world economy -- just happening few days before the New York primary.

[18:50:09] I assume he believes this visit to Vatican City will give him a boost with voters in New York.

BEINART: It's a fascinating example of the way this new pope has reshaped American politics. Now, you have, a pope for whatever reason or another basically giving -- you know, helping the political candidacy of a secular socialist running. Again, if you think about the former pope, Pope Benedict, who focused much more on conservative cultural issues, this really would have been really inconceivable. So, we seen in this move, the way in which changes in the Vatican are reverberating in American politics in really interest ways.

BLITZER: Very interesting ways indeed.

All right. Guys, stand by.

An important programming note to all of our viewers. Please be sure to tune in Sunday morning to "STATE OF THE UNION" with Jake Tapper. They'll be speaking exclusively with Hillary Clinton, as well as with Senator Bernie Sanders. That's at 9:00 a.m. Eastern, Noon Eastern, as well, only here on CNN.

Clinton and Sanders will go head to head six days from now. I'll be moderator for the CNN Democratic presidential debate in Brooklyn. That's Thursday night, 9:00 p.m. Eastern, only here on CNN.

Just ahead, more on the breaking news, the capture of the terror suspects in Europe. And the new searches that are under way right now.

(COMMERCIAL BREAK)

[18:56:25] BLITZER: We're following breaking news in the hunt for terrorists in Europe. New search is under way tonight after the arrest of suspects linked to the attacks in Paris and Brussels, including one of the world's most wanted fugitives, Mohamed Abrini.

Paul, what's the significance of this specific arrest of Mohamed Abrini?

PAUL CRUICKSHANK, CNN TERRORISM ANALYST: Wolf, it's a very significant breakthrough indeed. Both getting Mohamed Abrini and also getting Osama Kraiem. These were two integral members of the Paris and Brussels attack cell. They were regarded by European counterterrorism officials before today as the two most dangerous men in Europe. The two they most wanted to get. And 24 hours after Belgium police released that CCTV footage of the so-called third attacker in Europe, clearly there was a breakthrough. And they have now both of these men in custody.

These men will not be able to launch follow-on attacks. The worry, Wolf, though, there are others connected to this group. And we understand they believe there are more than a dozen others still at large connected to this group who may in the future carry out attacks.

And, of course, it was three weeks ago last Friday that -- or three weeks ago today, I should say, on a Friday, when they capture Salah Abdeslam. And an accomplice and the rest of this attack cell accelerated their plan. And so, to the worry this time around is the same sort of thing could happen again. The others still out there could be desperate, could feel that the dragnet is coming down on them and could proceed with attacks.

So, that's why the continuing searches tonight across Brussels, multiple operations in play that are trying to get others based on the intelligence that they obtained from these arrests and from all the other investigations they're doing, Wolf.

BLITZER: Clearly explains why they're still on a very high state of alert. As you know, Paul, the Belgium broadcaster BRT reports that Abrini was also possibly, possibly, they're so-called "man in a hat" sought in connection with the Brussels attacks. What are hearing from your sources? CRUICKSHANK: Wolf, in terms of the press conference today from the

Belgian prosecutor, they said they were investigating whether there was Abrini at the airport. They wanted to determine that for sure.

I think reading between the lines, they have something which makes them suspect this is Abrini, but they do not have that knowledge for sure at this point. They also used similar language when it came to Osama Kraiem, who they said they were investigating whether he was the second guy seen at the Brussels metro, that they wanted to verify that.

I think there is clearly some intelligence suggesting that that may be the case. But they're not going to make any announcement before they're absolutely sure.

BLITZER: We heard Senator Mark Warner of Virginia tell me earlier, that based on the intelligence committee, he thinks Belgium should raise its alert level right now. What do you think?

CRUICKSHANK: Well, it's already high. And the only place it could go is the highest level and that clearly is a decision which may be taken at some point by the threat center in Belgium, which is responsible for all of this. But that's only meant to ratchet it up to level four, the top level. If this fear of an imminent attack, you cannot have the level at four continuously. And that's why they lowered it back down to three. If they get that intelligence, they will raise it.

BLITZER: All right. Paul Cruickshank, thanks very much. We'll obviously stay on top of this story. That's it for me. Thanks very much for watching.